I’m Russ Jones, Principal Search Scientist at Moz, and I am excited to announce a fantastic upgrade coming next month to one of the most important metrics Moz offers: Domain Authority.

Domain Authority has become the industry standard for measuring the strength of a domain relative to ranking. We recognize that stability plays an important role in making Domain Authority valuable to our customers, so we wanted to make sure that the new Domain Authority brought meaningful changes to the table.

What’s changing?

What follows is an account of some of the technical changes behind the new Domain Authority and why they matter.

The training set:

Historically, we’ve relied on training Domain Authority against an unmanipulated, large set of search results. In fact, this has been the standard methodology across our industry. But we have found a way to improve upon it that fundamentally, from the ground up, makes Domain Authority more reliable.

The training algorithm:

Rather than relying on a complex linear model, we’ve made the switch to a neural network. This offers several benefits including a much more nuanced model which can detect link manipulation.

The model factors:

We have greatly improved upon the ranking factors behind Domain Authority. In addition to looking at link counts, we’ve now been able to integrate our proprietary Spam Score and complex distributions of links based on quality and traffic, along with a bevy of other factors.

The backbone:

At the heart of Domain Authority is the industry’s leading link index, our new Moz Link Explorer. With over 35 trillion links, our exceptional data turns the brilliant statistical work by Neil Martinsen-Burrell, Chas Williams, and so many more amazing Mozzers into a true industry standard.

What does this mean?

These fundamental improvements to Domain Authority will deliver a better, more trustworthy metric than ever before. We can remove spam, improve correlations, and, most importantly, update Domain Authority relative to all the changes that Google makes.

It means that you will see some changes to Domain Authority when the launch occurs. We staked the model to our existing Domain Authority which minimizes changes, but with all the improvements there will no doubt be some fluctuation in Domain Authority scores across the board.

What should we do?

Use DA as a relative metric, not an absolute one.

First, make sure that you use Domain Authority as a relative metric. Domain Authority is meaningless when it isn’t compared to other sites. What matters isn’t whether your site drops or increases — it’s whether it drops or increases relative to your competitors. When we roll out the new Domain Authority, make sure you check your competitors’ scores as well as your own, as they will likely fluctuate in a similar direction.

Know how to communicate changes with clients, colleagues, and stakeholders

Second, be prepared to communicate with your clients or webmasters about the changes and improvements to Domain Authority. While change is always disruptive, the new Domain Authority is better than ever and will allow them to make smarter decisions about search engine optimization strategies going forward.

Expect DA to keep pace with Google

Finally, expect that we will be continuing to improve Domain Authority. Just like Google makes hundreds of changes to their algorithm every year, we intend to make Domain Authority much more responsive to Google’s changes. Even when Google makes fundamental algorithm updates like Penguin or Panda, you can feel confident that Moz’s Domain Authority will be as relevant and useful as ever.

When is it happening?

We plan on rolling out the new Domain Authority on March 5th, 2019. We will have several more communications between now and then to help you and your clients best respond to the new Domain Authority, including a webinar on February 21st. We hope you’re as excited as we are and look forward to continuing to bring you the most reliable, cutting-edge metrics our industry has to offer.

Be sure to check out the resources we’ve prepared to help you acclimate to the change, including an educational whitepaper and a presentation you can download to share with your clients, team, and stakeholders:

Sign up for The Moz Top 10, a semimonthly mailer updating you on the top ten hottest pieces of SEO news, tips, and rad links uncovered by the Moz team. Think of it as your exclusive digest of stuff you don’t have time to hunt down but want to read!

Chapter 6: Link Building & Establishing Authority

Turn up the volume.

You’ve created content that people are searching for, that answers their questions, and that search engines can understand, but those qualities alone don’t mean it’ll rank. To outrank the rest of the sites with those qualities, you have to establish authority. That can be accomplished by earning links from authoritative websites, building your brand, and nurturing an audience who will help amplify your content.

Google has confirmed that links and quality content (which we covered back in Chapter 4) are two of the three most important ranking factors for SEO. Trustworthy sites tend to link to other trustworthy sites, and spammy sites tend to link to other spammy sites. But what is a link, exactly? How do you go about earning them from other websites? Let’s start with the basics.

What are links?

Inbound links, also known as backlinks or external links, are HTML hyperlinks that point from one website to another. They’re the currency of the Internet, as they act a lot like real-life reputation. If you went on vacation and asked three people (all completely unrelated to one another) what the best coffee shop in town was, and they all said, “Cuppa Joe on Main Street,” you would feel confident that Cuppa Joe is indeed the best coffee place in town. Links do that for search engines.

Since the late 1990s, search engines have treated links as votes for popularity and importance on the web.

Internal links, or links that connect internal pages of the same domain, work very similarly for your website. A high amount of internal links pointing to a particular page on your site will provide a signal to Google that the page is important, so long as it’s done naturally and not in a spammy way.

The engines themselves have refined the way they view links, now using algorithms to evaluate sites and pages based on the links they find. But what’s in those algorithms? How do the engines evaluate all those links? It all starts with the concept of E-A-T.

You are what you E-A-T

Google’s Search Quality Rater Guidelines put a great deal of importance on the concept of E-A-T — an acronym for expert, authoritative, and trustworthy. Sites that don’t display these characteristics tend to be seen as lower-quality in the eyes of the engines, while those that do are subsequently rewarded. E-A-T is becoming more and more important as search evolves and increases the importance of solving for user intent.

Creating a site that’s considered expert, authoritative, and trustworthy should be your guiding light as you practice SEO. Not only will it simply result in a better site, but it’s future-proof. After all, providing great value to searchers is what Google itself is trying to do.

E-A-T and links to your site

The more popular and important a site is, the more weight the links from that site carry. A site like Wikipedia, for example, has thousands of diverse sites linking to it. This indicates it provides lots of expertise, has cultivated authority, and is trusted among those other sites.

To earn trust and authority with search engines, you’ll need links from websites that display the qualities of E-A-T. These don’t have to be Wikipedia-level sites, but they should provide searchers with credible, trustworthy content.

Tip: Moz has proprietary metrics to help you determine how authoritative a site is: Domain Authority, Page Authority, and Spam Score. In general, you’ll want links from sites with a higher Domain Authority than your sites.

Followed vs. nofollowed links

Remember how links act as votes? The rel=nofollow attribute (pronounced as two words, “no follow”) allows you to link to a resource while removing your “vote” for search engine purposes.

Just like it sounds, “nofollow” tells search engines not to follow the link. Some engines still follow them simply to discover new pages, but these links don’t pass link equity (the “votes of popularity” we talked about above), so they can be useful in situations where a page is either linking to an untrustworthy source or was paid for or created by the owner of the destination page (making it an unnatural link).

Say, for example, you write a post about link building practices, and want to call out an example of poor, spammy link building. You could link to the offending site without signaling to Google that you trust it.

Standard links (ones that haven’t had nofollow added) look like this:

<a href="https://moz.com">I love Moz</a>

Nofollow link markup looks like this:

<a href="https://moz.com" rel="nofollow">I love Moz</a>

If follow links pass all the link equity, shouldn’t that mean you want only follow links?

Not necessarily. Think about all the legitimate places you can create links to your own website: a Facebook profile, a Yelp page, a Twitter account, etc. These are all natural places to add links to your website, but they shouldn’t count as votes for your website. (Setting up a Twitter profile with a link to your site isn’t a vote from Twitter that they like your site.)

It’s natural for your site to have a balance between nofollowed and followed backlinks in its link profile (more on link profiles below). A nofollow link might not pass authority, but it could send valuable traffic to your site and even lead to future followed links.

Tip: Use the MozBar extension for Google Chrome to highlight links on any page to find out whether they’re nofollow or follow without ever having to view the source code!

Your link profile

Your link profile is an overall assessment of all the inbound links your site has earned: the total number of links, their quality (or spamminess), their diversity (is one site linking to you hundreds of times, or are hundreds of sites linking to you once?), and more. The state of your link profile helps search engines understand how your site relates to other sites on the Internet. There are various SEO tools that allow you to analyze your link profile and begin to understand its overall makeup.

How can I see which inbound links point to my website?

Visit Moz Link Explorer and type in your site’s URL. You’ll be able to see how many and which websites are linking back to you.

What are the qualities of a healthy link profile?

When people began to learn about the power of links, they began manipulating them for their benefit. They’d find ways to gain artificial links just to increase their search engine rankings. While these dangerous tactics can sometimes work, they are against Google’s terms of service and can get a website deindexed (removal of web pages or entire domains from search results). You should always try to maintain a healthy link profile.

A healthy link profile is one that indicates to search engines that you’re earning your links and authority fairly. Just like you shouldn’t lie, cheat, or steal, you should strive to ensure your link profile is honest and earned via your hard work.

Links are earned or editorially placed

Editorial links are links added naturally by sites and pages that want to link to your website.

The foundation of acquiring earned links is almost always through creating high-quality content that people genuinely wish to reference. This is where creating 10X content (a way of describing extremely high-quality content) is essential! If you can provide the best and most interesting resource on the web, people will naturally link to it.

Naturally earned links require no specific action from you, other than the creation of worthy content and the ability to create awareness about it.

Tip: Earned mentions are often unlinked! When websites are referring to your brand or a specific piece of content you’ve published, they will often mention it without linking to it. To find these earned mentions, use Moz’s Fresh Web Explorer. You can then reach out to those publishers to see if they’ll update those mentions with links.

Links are relevant and from topically similar websites

Links from websites within a topic-specific community are generally better than links from websites that aren’t relevant to your site. If your website sells dog houses, a link from the Society of Dog Breeders matters much more than one from the Roller Skating Association. Additionally, links from topically irrelevant sources can send confusing signals to search engines regarding what your page is about.

Tip: Linking domains don’t have to match the topic of your page exactly, but they should be related. Avoid pursuing backlinks from sources that are completely off-topic; there are far better uses of your time.

Anchor text is descriptive and relevant, without being spammy

Anchor text helps tell Google what the topic of your page is about. If dozens of links point to a page with a variation of a word or phrase, the page has a higher likelihood of ranking well for those types of phrases. However, proceed with caution! Too many backlinks with the same anchor text could indicate to the search engines that you’re trying to manipulate your site’s ranking in search results.

Consider this. You ask ten separate friends at separate times how their day was going, and they each responded with the same phrase:

“Great! I started my day by walking my dog, Peanut, and then had a picante beef Top Ramen for lunch.”

That’s strange, and you’d be quite suspicious of your friends. The same goes for Google. Describing the content of the target page with the anchor text helps them understand what the page is about, but the same description over and over from multiple sources starts to look suspicious. Aim for relevance; avoid spam.

Tip: Use the “Anchor Text” report in Moz’s Link Explorer to see what anchor text other websites are using to link to your content.

Links send qualified traffic to your site

Link building should never be solely about search engine rankings. Esteemed SEO and link building thought leader Eric Ward used to say that you should build your links as though Google might disappear tomorrow. In essence, you should focus on acquiring links that will bring qualified traffic to your website — another reason why it’s important to acquire links from relevant websites whose audience would find value in your site, as well.

Tip: Use the “Referral Traffic” report in Google Analytics to evaluate websites that are currently sending you traffic. How can you continue to build relationships with similar types of websites?

Link building don’ts & things to avoid

Spammy link profiles are just that: full of links built in unnatural, sneaky, or otherwise low-quality ways. Practices like buying links or engaging in a link exchange might seem like the easy way out, but doing so is dangerous and could put all of your hard work at risk. Google penalizes sites with spammy link profiles, so don’t give in to temptation.

A guiding principle for your link building efforts is to never try to manipulate a site’s ranking in search results. But isn’t that the entire goal of SEO? To increase a site’s ranking in search results? And herein lies the confusion. Google wants you to earn links, not build them, but the line between the two is often blurry. To avoid penalties for unnatural links (known as “link spam”), Google has made clear what should be avoided.

Purchased links

Google and Bing both seek to discount the influence of paid links in their organic search results. While a search engine can’t know which links were earned vs. paid for from viewing the link itself, there are clues it uses to detect patterns that indicate foul play. Websites caught buying or selling followed links risk severe penalties that will severely drop their rankings. (By the way, exchanging goods or services for a link is also a form of payment and qualifies as buying links.)

Link exchanges / reciprocal linking

If you’ve ever received a “you link to me and I’ll link you you” email from someone you have no affiliation with, you’ve been targeted for a link exchange. Google’s quality guidelines caution against “excessive” link exchange and similar partner programs conducted exclusively for the sake of cross-linking, so there is some indication that this type of exchange on a smaller scale might not trigger any link spam alarms.

It is acceptable, and even valuable, to link to people you work with, partner with, or have some other affiliation with and have them link back to you.

It’s the exchange of links at mass scale with unaffiliated sites that can warrant penalties.

Low-quality directory links

These used to be a popular source of manipulation. A large number of pay-for-placement web directories exist to serve this market and pass themselves off as legitimate, with varying degrees of success. These types of sites tend to look very similar, with large lists of websites and their descriptions (typically, the site’s critical keyword is used as the anchor text to link back to the submittor’s site).

There are many more manipulative link building tactics that search engines have identified. In most cases, they have found algorithmic methods for reducing their impact. As new spam systems emerge, engineers will continue to fight them with targeted algorithms, human reviews, and the collection of spam reports from webmasters and SEOs. By and large, it isn’t worth finding ways around them.

How to build high-quality backlinks

Link building comes in many shapes and sizes, but one thing is always true: link campaigns should always match your unique goals. With that said, there are some popular methods that tend to work well for most campaigns. This is not an exhaustive list, so visit Moz’s blog posts on link building for more detail on this topic.

Find customer and partner links

If you have partners you work with regularly, or loyal customers that love your brand, there are ways to earn links from them with relative ease. You might send out partnership badges (graphic icons that signify mutual respect), or offer to write up testimonials of their products. Both of those offer things they can display on their website along with links back to you.

Publish a blog

This content and link building strategy is so popular and valuable that it’s one of the few recommended personally by the engineers at Google. Blogs have the unique ability to contribute fresh material on a consistent basis, generate conversations across the web, and earn listings and links from other blogs.

Careful, though — you should avoid low-quality guest posting just for the sake of link building. Google has advised against this and your energy is better spent elsewhere.

Create unique resources

Creating unique, high quality resources is no easy task, but it’s well worth the effort. High quality content that is promoted in the right ways can be widely shared. It can help to create pieces that have the following traits:

Creating a resource like this is a great way to attract a lot of links with one page. You could also create a highly-specific resource — without as broad of an appeal — that targeted a handful of websites. You might see a higher rate of success, but that approach isn’t as scalable.

Users who see this kind of unique content often want to share it with friends, and bloggers/tech-savvy webmasters who see it will often do so through links. These high quality, editorially earned votes are invaluable to building trust, authority, and rankings potential.

Build resource pages

Resource pages are a great way to build links. However, to find them you’ll want to know some Advanced Google operators to make discovering them a bit easier.

For example, if you were doing link building for a company that made pots and pans, you could search for: cooking intitle:”resources” and see which pages might be good link targets.

This can also give you great ideas for content creation — just think about which types of resources you could create that these pages would all like to reference/link to.

Get involved in your local community

For a local business (one that meets its customers in person), community outreach can result in some of the most valuable and influential links.

Engage in sponsorships and scholarships.

Host or participate in community events, seminars, workshops, and organizations.

Donate to worthy local causes and join local business associations.

Post jobs and offer internships.

Promote loyalty programs.

Run a local competition.

Develop real-world relationships with related local businesses to discover how you can team up to improve the health of your local economy.

All of these smart and authentic strategies provide good local link opportunities.

Refurbish top content

You likely already know which of your site’s content earns the most traffic, converts the most customers, or retains visitors for the longest amount of time.

You can also dust off, update, and simply republish older content on the same platform. If you discover that a few trusted industry websites all linked to a popular resource that’s gone stale, update it and let those industry websites know — you may just earn a good link.

You can also do this with images. Reach out to websites that are using your images and not citing/linking back to you and ask if they’d mind including a link.

Be newsworthy

Earning the attention of the press, bloggers, and news media is an effective, time-honored way to earn links. Sometimes this is as simple as giving something away for free, releasing a great new product, or stating something controversial. Since so much of SEO is about creating a digital representation of your brand in the real world, to succeed in SEO, you have to be a great brand.

Be personal and genuine

The most common mistake new SEOs make when trying to build links is not taking the time to craft a custom, personal, and valuable initial outreach email. You know as well as anyone how annoying spammy emails can be, so make sure yours doesn’t make people roll their eyes.

Your goal for an initial outreach email is simply to get a response. These tips can help:

Make it personal by mentioning something the person is working on, where they went to school, their dog, etc.

Provide value. Let them know about a broken link on their website or a page that isn’t working on mobile.

Keep it short.

Ask one simple question (typically not for a link; you’ll likely want to build a rapport first).

Pro Tip:

Earning links can be very resource-intensive, so you’ll likely want to measure your success to prove the value of those efforts.

Metrics for link building should match up with the site’s overall KPIs. These might be sales, email subscriptions, page views, etc. You should also evaluate Domain and/or Page Authority scores, the ranking of desired keywords, and the amount of traffic to your content — but we’ll talk more about measuring the success of your SEO campaigns in Chapter 7.

A lot of the methods you’d use to build links will also indirectly build your brand. In fact, you can view link building as a great way to increase awareness of your brand, the topics on which you’re an authority, and the products or services you offer.

Once your target audience knows about you and you have valuable content to share, let your audience know about it! Sharing your content on social platforms will not only make your audience aware of your content, but it can also encourage them to amplify that awareness to their own networks, thereby extending your own reach.

Are social shares the same as links? No. But shares to the right people can result in links. Social shares can also promote an increase in traffic and new visitors to your website, which can grow brand awareness, and with a growth in brand awareness can come a growth in trust and links. The connection between social signals and rankings seems indirect, but even indirect correlations can be helpful for informing strategy.

Trustworthiness goes a long way

For search engines, trust is largely determined by the quality and quantity of the links your domain has earned, but that’s not to say that there aren’t other factors at play that can influence your site’s authority. Think about all the different ways you come to trust a brand:

Awareness (you know they exist)

Helpfulness (they provide answers to your questions)

Integrity (they do what they say they will)

Quality (their product or service provides value; possibly more than others you’ve tried)

Continued value (they continue to provide value even after you’ve gotten what you needed)

Voice (they communicate in unique, memorable ways)

Sentiment (others have good things to say about their experience with the brand)

That last point is what we’re going to focus on here. Reviews of your brand, its products, or its services can make or break a business.

In your effort to establish authority from reviews, follow these review rules of thumb:

Never pay any individual or agency to create a fake positive review for your business or a fake negative review of a competitor.

Don’t review your own business or the businesses of your competitors. Don’t have your staff do so either.

Never offer incentives of any kind in exchange for reviews.

All reviews must be left directly by customers in their own accounts; never post reviews on behalf of a customer or employ an agency to do so.

Don’t set up a review station/kiosk in your place of business; many reviews stemming from the same IP can be viewed as spam.

Read the guidelines of each review platform where you’re hoping to earn reviews.

Be aware that review spam is a problem that’s taken on global proportions, and that violation of governmental truth-in-advertising guidelines has led to legal prosecution and heavy fines. It’s just too dangerous to be worth it. Playing by the rules and offering exceptional customer experiences is the winning combination for building both trust and authority over time.

Authority is built when brands are doing great things in the real-world, making customers happy, creating and sharing great content, and earning links from reputable sources.

In the next and final section, you’ll learn how to measure the success of all your efforts, as well as tactics for iterating and improving upon them. Onward!

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Correlation studies have been a staple of the search engine optimization community for many years. Each time a new study is released, a chorus of naysayers seem to come magically out of the woodwork to remind us of the one thing they remember from high school statistics — that “correlation doesn’t mean causation.” They are, of course, right in their protestations and, to their credit, and unfortunate number of times it seems that those conducting the correlation studies have forgotten this simple aphorism.

We collect a search result. We then order the results based on different metrics like the number of links. Finally, we compare the orders of the original search results with those produced by the different metrics. The closer they are, the higher the correlation between the two.

That being said, correlation studies are not altogether fruitless simply because they don’t necessarily uncover causal relationships (ie: actual ranking factors). What correlation studies discover or confirm are correlates.

Correlates are simply measurements that share some relationship with the independent variable (in this case, the order of search results on a page). For example, we know that backlink counts are correlates of rank order. We also know that social shares are correlates of rank order.

Correlation studies also provide us with direction of the relationship. For example, ice cream sales are positive correlates with temperature and winter jackets are negative correlates with temperature — that is to say, when the temperature goes up, ice cream sales go up but winter jacket sales go down.

Finally, correlation studies can help us rule out proposed ranking factors. This is often overlooked, but it is an incredibly important part of correlation studies. Research that provides a negative result is often just as valuable as research that yields a positive result. We’ve been able to rule out many types of potential factors — like keyword density and the meta keywords tag — using correlation studies.

Unfortunately, the value of correlation studies tends to end there. In particular, we still want to know whether a correlate causes the rankings or is spurious. Spurious is just a fancy sounding word for “false” or “fake.” A good example of a spurious relationship would be that ice cream sales cause an increase in drownings. In reality, the heat of the summer increases both ice cream sales and people who go for a swim. That swimming can cause drownings. So while ice cream sales is a correlate of drowning, it is *spurious.* It does not cause the drowning.

How might we go about teasing out the difference between causal and spurious relationships? One thing we know is that a cause happens before its effect, which means that a causal variable should predict a future change.

An alternative model for correlation studies

I propose an alternate methodology for conducting correlation studies. Rather than measure the correlation between a factor (like links or shares) and a SERP, we can measure the correlation between a factor and changes in the SERP over time.

The process works like this:

Collect a SERP on day 1

Collect the link counts for each of the URLs in that SERP

Look for any URLs are out of order with respect to links; for example, if position 2 has fewer links than position 3

Record that anomaly

Collect the same SERP in 14 days

Record if the anomaly has been corrected (ie: position 3 now out-ranks position 2)

Repeat across ten thousand keywords and test a variety of factors (backlinks, social shares, etc.)

So what are the benefits of this methodology? By looking at change over time, we can see whether the ranking factor (correlate) is a leading or lagging feature. A lagging feature can automatically be ruled out as causal. A leading factor has the potential to be a causal factor.

We collect a search result. We record where the search result differs from the expected predictions of a particular variable (like links or social shares). We then collect the same search result 2 weeks later to see if the search engine has corrected the out-of-order results.

Following this methodology, we tested 3 different common correlates produced by ranking factors studies: Facebook shares, number of root linking domains, and Page Authority. The first step involved collecting 10,000 SERPs from randomly selected keywords in our Keyword Explorer corpus. We then recorded Facebook Shares, Root Linking Domains, and Page Authority for every URL. We noted every example where 2 adjacent URLs (like positions 2 and 3 or 7 and were flipped with respect to the expected order predicted by the correlating factor. For example, if the #2 position had 30 shares while the #3 position had 50 shares, we noted that pair. Finally, 2 weeks later, we captured the same SERPs and identified the percent of times that Google rearranged the pair of URLs to match the expected correlation. We also randomly selected pairs of URLs to get a baseline percent likelihood that any 2 adjacent URLs would switch positions. Here were the results…

The outcome

It’s important to note that it is incredibly rare to expect a leading factor to show up strongly in an analysis like this. While the experimental method is sound, it’s not as simple as a factor predicting future — it assumes that in some cases we will know about a factor before Google does. The underlying assumption is that in some cases we have seen a ranking factor (like an increase in links or social shares) before Googlebot has and that in the 2 week period, Google will catch up and correct the incorrectly ordered results. As you can expect, this is a rare occasion. However, with a sufficient number of observations, we should be able to see a statistically significant difference between lagging and leading results. However, the methodology only detects when a factor is both leading and Moz Link Explorer discovered the relevant factor before Google.

Factor

Percent Corrected

P-Value

95% Min

95% Max

Control

18.93%

0

Facebook Shares Controlled for PA

18.31%

0.00001

-0.6849

-0.5551

Root Linking Domains

20.58%

0.00001

0.016268

0.016732

Page Authority

20.98%

0.00001

0.026202

0.026398

Control:

In order to create a control, we randomly selected adjacent URL pairs in the first SERP collection and determined the likelihood that the second will outrank the first in the final SERP collection. Approximately 18.93% of the time the worse ranking URL would overtake the better ranking URL. By setting this control, we can determine if any of the potential correlates are leading factors – that is to say that they are potential causes of improved rankings.

Facebook Shares:

Facebook Shares performed the worst of the three tested variables. Facebook Shares actually performed worse than random (18.31% vs 18.93%), meaning that randomly selected pairs would be more likely to switch than those where shares of the second were higher than the first. This is not altogether surprising as it is the general industry consensus that social signals are lagging factors — that is to say the traffic from higher rankings drives higher social shares, not social shares drive higher rankings. Subsequently, we would expect to see the ranking change first before we would see the increase in social shares.

RLDs

Raw root linking domain counts performed substantially better than shares at ~20.5%. As I indicated before, this type of analysis is incredibly subtle because it only detects when a factor is both leading and Moz Link Explorer discovered the relevant factor before Google. Nevertheless, this result was statistically significant with a P value <0.0001 and a 95% confidence interval that RLDs will predict future ranking changes around 1.5% greater than random.

Page Authority

By far, the highest performing factor was Page Authority. At 21.5%, PA correctly predicted changes in SERPs 2.6% better than random. This is a strong indication of a leading factor, greatly outperforming social shares and outperforming the best predictive raw metric, root linking domains.This is not unsurprising. Page Authority is built to predict rankings, so we should expect that it would outperform raw metrics in identifying when a shift in rankings might occur. Now, this is not to say that Google uses Moz Page Authority to rank sites, but rather that Moz Page Authority is a relatively good approximation of whatever link metrics Google is using to determine ranking sites.

Concluding thoughts

There are so many different experimental designs we can use to help improve our research industry-wide, and this is just one of the methods that can help us tease out the differences between causal ranking factors and lagging correlates. Experimental design does not need to be elaborate and the statistics to determine reliability do not need to be cutting edge. While machine learning offers much promise for improving our predictive models, simple statistics can do the trick when we’re establishing the fundamentals.

Now, get out there and do some great research!

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Authority Pro is a fresh new design by our Lead Designer Rafal Tomal and the team at StudioPress. The big idea behind this specific design is to help you put the full extent of your expertise on display. Consistently demonstrating your likable expertise over time is what allows you to build meaningful and lasting trust Read More…

How can you effectively apply link metrics like Domain Authority and Page Authority alongside your other SEO metrics? Where and when does it make sense to take them into account, and what exactly do they mean? In today’s Whiteboard Friday, Rand answers these questions and more, arming you with the knowledge you need to better understand and execute your SEO work.

Click on the whiteboard image above to open a high-resolution version in a new tab!

Video Transcription

Howdy, Moz fans, and welcome to another edition of Whiteboard Friday. This week we’re going to chat about when and how to use Domain Authority and Page Authority and link count metrics.

So many of you have written to us at Moz over the years and certainly I go to lots of conferences and events and speak to folks who are like, “Well, I’ve been measuring my link building activity with DA,” or, “Hey, I got a high DA link,” and I want to confirm when is it the right time to be using something like DA or PA or a raw link count metric, like number of linking root domains or something like Spam Score or a traffic estimation, these types of metrics.

So I’m going to walk you through kind of these three — Page Authority, Domain Authority, and linking root domains — just to get a refresher course on what they are. Page Authority and Domain Authority are actually a little complicated. So I think that’s worthwhile. Then we’ll chat about when to use which metrics. So I’ve got sort of the three primary things that people use link metrics for in the SEO world, and we’ll walk through those.

Page Authority

So to start, Page Authority is basically — you can see I’ve written a ton of different little metrics in here — linking URLs, linking root domains, MozRank, MozTrust, linking subdomains, anchor text, linking pages, followed links, no followed links, 301s, 302s, new versus old links, TLD, domain name, branded domain mentions, Spam Score, and many, many other metrics.

Basically, what PA is, is it’s every metric that we could possibly come up with from our link index all taken together and then thrown into a model with some training data. So the training data in this case, quite obviously, is Google search results, because what we want the Page Authority score to ultimately be is a predictor of how well a given page is going to rank in Google search results assuming we know nothing else about it except link data. So this is using no on-page data, no content data, no engagement or visit data, none of the patterns or branding or entity matches, just link data.

So this is everything we possibly know about a page from its link profile and the domain that page is on, and then we insert that in as the input alongside the training data. We have a machine learning model that essentially learns against Google search results and builds the best possible model it can. That model, by the way, throws away some of this stuff, because it’s not useful, and it adds in a bunch of this stuff, like vectors or various attributes of each one. So it might say, “Oh, anchor text distribution, that’s actually not useful, but Domain Authority ordered by the root domains with more than 500 links to them.” I’m making stuff up, right? But you could have those sorts of filters on this data and thus come up with very complex models, which is what machine learning is designed to do.

All we have to worry about is that this is essentially the best predictive score we can come up with based on the links. So it’s useful for a bunch of things. If we’re trying to say how well do we think this page might rank independent of all non-link factors, PA, great model. Good data for that.

Domain Authority

Domain Authority is once you have the PA model in your head and you’re sort of like, “Okay, got it, machine learning against Google’s results to produce the best predictive score for ranking in Google.” DA is just the PA model at the root domain level. So not subdomains, just root domains, which means it’s got some weirdness. It can’t, for example, say that randfishkin.blogspot.com is different than www.blogspot.com. But obviously, a link from www.blogspot.com is way more valuable than from my personal subdomain at Blogspot or Tumblr or WordPress or any of these hosted subdomains. So that’s kind of an edge case that unfortunately DA doesn’t do a great job of supporting.

What it’s good for is it’s relatively well-suited to be predictive of how a domain’s pages will rank in Google. So it removes all the page-level information, but it’s still operative at the domain level. It can be very useful for that.

Linking Root Domain

Then linking root domains is the simplest one. This is basically a count of all the unique root domains with at least one link on them that point to a given page or a site. So if I tell you that this URL A has 410 linking root domains, that basically means that there are 410 domains with at least one link pointing to URL A.

What I haven’t told you is whether they’re followed or no followed. Usually, this is a combination of those two unless it’s specified. So even a no followed link could go into the linking root domains, which is why you should always double check. If you’re using Ahrefs or Majestic or Moz and you hover on the whatever, the little question mark icon next to any given metric, it will tell you what it includes and what it doesn’t include.

When to use which metric(s)

All right. So how do we use these?

Well, for month over month link building performance, which is something that a lot of folks track, I would actually not suggest making DA your primary one. This is for a few reasons. So Moz’s index, which is the only thing currently that calculates DA or a machine learning-like model out there among the major toolsets for link data, only updates about once every month. So if you are doing your report before the DA has updated from the last link index, that can be quite frustrating.

Now, I will say we are only a few months away from a new index that’s going to replace Mozscape that will calculate DA and PA and all these other things much, much more quickly. I know that’s been something many folks have been asking for. It is on its way.

But in the meantime, what I recommend using is:

1. Linking root domains, the count of linking root domains and how that’s grown over time.

2. Organic rankings for your targeted keywords. I know this is not a direct link metric, but this really helps to tell you about the performance of how those links have been affected. So if you’re measuring month to month, it should be the case that any months you’ve got in a 20 or 30-day period, Google probably has counted and recognized within a few days of finding them, and Google is pretty good at crawling nearly the whole web within a week or two weeks. So this is going to be a reasonable proxy for how your link building campaign has helped your organic search campaign.

3. The distribution of Domain Authority. So I think, in this case, Domain Authority can be useful. It wouldn’t be my first or second choice, but I think it certainly can belong in a link building performance report. It’s helpful to see the high DA links that you’re getting. It’s a good sorting mechanism to sort of say, “These are, generally speaking, more important, more authoritative sites.”

4. Spam Score I like as well, because if you’ve been doing a lot of link building, it is the case that Domain Authority doesn’t penalize or doesn’t lower its score for a high Spam Score. It will show you, “Hey, this is an authoritative site with a lot of DA and good-looking links, but it also looks quite spammy to us.” So, for example, you might see that something has a DA of 60, but a Spam Score of 7 or 8, which might be mildly concerning. I start to really worry when you get to like 9, 10, or 11.

Second question:

I think this is something that folks ask. So they look at their own links and they say, “All right, we have these links or our competitor has these links. Which ones are providing the most value for me?” In that case, if you can get it, for example, if it’s a link pointing to you, the best one is, of course, going to be…

1. Real traffic sent. If a site or a page, a link is sending traffic to you, that is clearly of value and that’s going to be likely interpreted positively by the search engines as well.

You can also use…

2. PA

3. DA. I think it’s pretty good. These metrics are pretty good and pretty well-correlated with, relatively speaking, value, especially if you can’t get at a metric like real traffic because it’s coming from someone else’s site.

4. Linking root domains, the count of those to a page or a domain.

5. The rankings rise, in the case where a page is ranking position four, a new link coming to it is the only thing that’s changed or the only thing you’re aware of that’s changed in the last few days, few weeks, and you see a rankings rise. It moves up a few positions. That’s a pretty good proxy for, “All right, that is a valuable link.” But this is a rare case where you really can control other variables to the extent that you think you can believe in that.

6. I like Spam Scor for this as well, because then you can start to see, “Well, are these sketchier links, or are these links that I can likely trust more?”

Last one,

So I think this is one that many, many SEOs do. We have a big list of links. We’ve got 50 links that we’re thinking about, “Should I get these or not and which ones should I go after first and which ones should I not go after?” In this case…

1. DA is really quite a good metric, and that is because it’s relatively predictive of the domain’s pages’ performance in Google, which is a proxy, but a decent proxy for how it might help your site rank better.

It is the case that folks will talk about, “Hey, it tends to be the case that when I go out and I build lots of DA 70, DA 80, DA 90+ links, I often get credit. Why DA and not PA, Rand?” Well, in the case where you’re getting links, it’s very often from new pages on a website, which have not yet been assigned PA or may not have inherited all the link equity from all the internal pages.

Over time, as those pages themselves get more links, their PA will rise as well. But the reason that I generally recommend a DA for link outreach is both because of that PA/DA timing issue and because oftentimes you don’t know which page is going to give you a link from a domain. It could be a new page they haven’t created yet. It could be one that you never thought they would add you to. It might be exactly the page that you were hoping for, but it’s hard to say.

2. I think linking root domains is a very reasonable one for this, and linking root domains is certainly closely correlated, not quite as well correlated, but closely correlated with DA and with rankings.

3. Spam Score, like we’ve talked about.

4. I might use something like SimilarWeb‘s traffic estimates, especially if real traffic sent is something that I’m very interested in. If I’m pursuing no followed links or affiliate links or I just care about traffic more than I care about rank-boosting ability, SimilarWeb has got what I think is the best traffic prediction system, and so that would be the metric I look at.

So, hopefully, you now have a better understanding of DA and PA and link counts and when and where to apply them alongside which other metrics. I look forward to your questions. I’ll be happy to jump into the comments and answer. And we’ll see you again next time for another edition of Whiteboard Friday. Take care.

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